Conventionally, there is a signal detection device for detecting an input signal that includes noise. This signal detection device has N comparison units for comparing respective N parallel input signals (wherein N is a natural number equal to or greater than 2) with threshold values, respectively, and a computing unit for computing the number N+ of comparison units with the respective input signals greater than the threshold values. This signal detection device further has analysis means for computing a ratio N+/N of the number N+ of comparison units with the respective input signals greater than the threshold values to the number N of elements of the comparison units, based on an output from the computing unit, and estimating waveforms of the input signals by using this ratio of N+/N and statistics of noise (see, for example, Japanese Patent Application Publication No. 2010-045622).
Because a conventional signal detection device as described above uses N comparison units for comparing input signals with N threshold values, respectively, for example, 3 comparison units are needed to compare input signals with 3 threshold values.
Thus, there is a problem of a high electric power consumption of a conventional signal detection device because N comparison units are used to compare input signals with N threshold values, respectively.